This invention relates to electrical devices for mounting electrical components and methods of producing the same, and more particularly to such devices and methods by which a variety of electrical components can be assembled compactly with enhanced assembling efficiency.
FIG. 2 is a circuit diagram of an electrical device disclosed, for example, in Japanese laid-open utility model application No. 60-151186. FIG. 3 is a top view of the electrical device for mounting electrical components of the circuit of FIG. 2, and FIGS. 4 and 5 show the sections along the lines A--A and B--B of FIG. 3, respectively. As shown in FIG. 2, the circuit is an inverter circuit for converting the frequency, etc., of a three-phase power, and thus includes: an electromagnetic contactor 1 for turning on and off the power; reactors 2; control transformer 3 for converting the input voltage to a predetermined voltage level; diode bridge rectifier circuit 4 for rectifying the AC current; smoothing capacitor 5 for smoothing the DC current rectified via the diode bridge rectifier circuit 4; discharge transistor 6 for discharging the current charging the capacitors such as smoothing capacitor 5; and transistor inverter circuit 7 for converting the DC current, smoothed via the smoothing capacitor 5, into an AC current of desired frequency.
Finned aluminum base 8 radiates the heat generated by the transistor invertor circuit 7. Mold resin box 9 accommodates the electromagnetic contactor 1, the reactors 2, the control transformer 3, and the smoothing capacitor 5. An electrically insulating substrate 10 is provided with short bars for making large-current-carrying electrical connections among the terminals 14 of the electromagnetic contactor 1, the smoothing capacitor 5, the transistor invertor circuit 7, etc. A printed circuit board 11 includes electronic elements for generating control signals. The mold resin box 9 is provided with a cover 12 (removed in FIGS. 3 and 5).
The electrical components are fixed via screws on finned aluminum base 8 or within mold resin box 9, in such a manner that the terminals 14 of the electrical components are leveled in their height. The electrically insulating substrate 10 is disposed above the electrical components, such that the short bars on the electrically insulating substrate 10 are in contact with the terminals 14 of the electrical components. The printed circuit board 11 is positioned above the electrically insulating substrate 10 with a predetermined gap formed therebetween. Screws 13 extending through the printed circuit board 11 and the short bars and the electrically insulating substrate 10 secure the electrically insulating substrate 10 and the printed circuit board 11 such that secure electrical connections among the electrical components are ensured. It is noted that the finned aluminum base 8 carries the electrical components which generate a large amount of heat.
The above electrical device for mounting electrical components has the following disadvantages. First, since the electrical components are fixed via screws on the mold resin box 9 and the finned aluminum base 8, precise positioning of the electrical components is difficult to accomplish. Second, if the terminals 14 are not at the same level, the short bars are deformed or their electrical contacts with the terminals 14 of the electrical components may fail. In order to make equal the heights of the terminals 14, it is necessary to extend the length of some of the terminals or to interpose spacers between some of the electrical components and the bases. This precise leveling of the terminals is difficult to accomplish. Finally and thirdly, since a separate finned aluminum base 8 is necessary for radiating the heat of heat generating electrical components, the device is in need of two bases, the finned aluminum base 8 and the mold resin box 9. Thus, it is difficult to reduce the overall size of the electrical device for mounting electrical components.